Xie et al. found that the probiotic Clostridium butyricum was both depleted in patients with CRC and potentiated anti-PD-1 efficacy in mouse models of CRC (orthotopic MSI-H and MSS). Single-cell RNAseq showed that C. butyricum synergized with anti-PD-1 to activate cytotoxic CD8+ T cells and decrease TAM infiltration. Mechanistically, C. butyricum mediated its effect via binding of its surface protein secD to CRC-surface-expressed GRP78, resulting in downregulation of the PI3K–AKT–NF-kB pathway and reduced IL-6 secretion. Translational validation was achieved in huCD34+ humanized mice and autologous patient-derived CRC organoid–CTL cocultures.
Contributed by Katherine Turner
ABSTRACT: Most colorectal cancer (CRC) patients do not respond to immune checkpoint blockade (ICB) therapy. Here, we identify Clostridium butyricum as a probiotic that boosts anti-PD-1 efficacy in CRC. In orthotopic allografts of microsatellite instability-high (MSI-H) and microsatellite stable (MSS) CRC, C. butyricum potentiates tumor suppressive effect of anti-PD-1, which is verified in AOM/DSS-induced CRC and germ-free mice. Single-cell RNA-seq reveals that C. butyricum activates cytotoxic CD8+ T lymphocytes (CTLs) and impairs tumor-associated macrophages (TAMs), especially in conjunction with anti-PD-1. Mechanistically, C. butyricum surface protein secD binds to CRC cell receptor glucose-regulated protein 78 (GRP78), which inactivates GRP78 and PI3K-AKT-NF-κB pathway, leading to reduced secretion of interleukin (IL)-6, an immunosuppressive cytokine that blunts CTLs and induces TAMs. Translational impact of C. butyricum in boosting anti-PD-1 efficacy is validated in huCD34+ humanized mice and autologous patient-derived CRC organoids-CTLs co-culture system. To summarize, C. butyricum is a promising adjuvant to augment ICB therapy.
Author Info: (1) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen R
Author Info: (1) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (2) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (3) Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China. (4) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (5) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (6) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (7) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (8) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (9) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (10) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (11) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (12) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (13) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. (14) Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: junyu@cuhk.edu.hk.
